Jacob Asmar and his family discovered the message "convert or die" scrawled on the walls of their pizzeria in red paint earlier this week.
"I think it's horrible because we get thoughts that we don't want to get now (...) like we are going to die because this terrorist group is coming to Gothenburg," the 16-year-old told The Local on Friday.
"We Assyrians are worried - especially my family because we own the restaurant - about how there could be big trouble."
The pizzeria is one of a number of businesses in the Tynnered area of the city that have been targeted by graffiti appearing to support the radical Islamist group Isis (also known as IS) in recent weeks.
"It feels like persecution of Jews in the 30s when Jews in Germany had Stars of David painted on its doors. Now it happens here," said Jacob's father Yusuf Asmar in a separate interview with The Gothenburg Post.
Around 10,000 Assyrians, a Christian ethnic group originating in the region that is modern Syria, Iraq, Iran and Turkey - now live in Sweden.
Representatives of several Assyrian associations called an emergency meeting on Thursday night to discuss ongoing claims that Sweden's second largest city is becoming a recruitment hub for Isis, which has already targeted the Christian minority in Syria.
"Imagine if you fled persecution from your country and then started living next door to IS sympathisers here in Sweden. It is everyday life for many people," said Josef Garis, president of Assyriska Distriktet i Göteborg, one of the largest community groups for Assyrians in west Sweden.
"We know that Gothenburg is one of IS' recruitment bases, and we hear about people who express sympathy for IS here in Tynnered," he told the Gothenburg Post.
Jacob Asmar, who has Syrian parents but grew up in Sweden, told The Local he felt the mood was "definitely" changing in his home city as fighting continues in Syria, causing more citizens to flee to the Nordic nation and elsewhere in Europe.
"All those people who are coming to Gothenburg (...) I don't think they are all good people. I think many of them are from this terrorist group. They want the whole of Europe to be like them and they are coming to Europe for that [reason]."
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Police in the city say they are investigating the graffiti but have admitted that it may be difficult to get to the bottom of the alleged recent vandalism crimes.
"With no witnesses or forensic evidence that can be traced, it is almost impossible to investigate such cases. The only possibility is if someone has seen something and we get tips from the public," Bertil Claesson, a spokesperson for the force explained to the Gothenburg Post.
But there are concerns among Assyrians that officers need to be prioritising their fears.
"I think the police should take more responsibility (..) I mean they are, but in Sweden if they don't get any clues about the case they close the case after a couple of weeks and that's not good," Asmar told The Local.
Meanwhile Sweden's national coordinator Mona Sahlin waded into the debate on Friday, comparing Isis propaganda in Sweden to Nazi swastikas.
"I hope that people can view the IS flag in the same way as the swastika. Then they can also intervene when they see the symbol," she told Swedish public broadcaster Sveriges Radio, describing the Islamist organisation as "the world's most dangerous terrorist group".
Jonas Ransgård, vice president of Gothenburg municipal council and a member of the centre-right Moderate party, added: "The threats now directed at individuals are therefore also a threat to Gothenburg and against Sweden."
He also told the broadcaster: "It's disgusting, it's reprehensible and it's very serious."